NIFEDIPINE AND CAPTOPRIL EXERT DIVERGENT EFFECTS ON HEART-RATE-VARIABILITY IN PATIENTS WITH ACUTE EPISODES OF HYPERTENSION

Acute changes of heart rate variability (HRV) depict alterations in au tonomic influences on cardiovascular system and often precede ventricu lar arrhythmias. The aim of the study was to assess effects of subling ual 10 mg nifedipine (n = 15) or 25 mg captopril (n = 13) on HRV in co nsecutive patients admitted to hospital due to severe hypertension. HR V was calculated on-line from 300 cardiac cycles before and 60-90 min after drug administration. At baseline systolic blood pressure (SBP) w as >190 mm Hg and/or diastolic blood pressure (DBP) >110 mmHg. Both ag ents caused similar reduction of blood pressure (BP). Nifedipine reduc ed variance (-63 +/- 6%; P <0.0001) and high-frequency (HF) component (-72 +/- 8%; P <0.0001), and increased both LF/HF ratio (+870 +/- 336% ; P<0.02) and heart rate (+14 +/- 3%; P<0.0001). Captopril exerted dif ferent effects: variance and HF component increased by (P<0.007) and 126 +/- 44% (P<0.015), LF/HF (low/high frequency) ratio decreased (-44 +/- 19%; P < 0.04) together with heart rate (-4 +/- 1%; <0.009). It i s concluded that captopril, in contrast to nifedipine, increases HRV a nd decreases LF/HF ratio and therefore is a better choice in hypertens ive patients who might be prone to dangerous arrhythmias.